Biology Reference
In-Depth Information
A
UvrB
UvrA
2
RNAP
Mfd
RNA polymerase arrests at a lesion.
Mfd
binds RNA polymerase.
Mfd
recruits UvrA
2
.
RNA
UvrB
RNA polymerase and RNA are released.
UvrA
2
binds at or near the damaged site.
Mfd
B
UvrB
UvrA
2
UvrA
2
slightly bends the DNA.
Mfd
dissociates.
UvrB
UvrA
2
hands off the DNA to two UvrB
monomers, causing more DNA bending
and possibly wrapping, releasing UvrA
2
.
UvrC
UvrC binds to the UvrB-DNA complex.
A bubble (~13 nt) is opened.
UvrC catalyzes dual incisions.
UvrD
UvrD and Pol I excise the
oligonucleotide.
Pol I
Ligase
PolI and DNA ligase catalyze
repair synthesis and ligation.
F
IG
. 1. Transcription-coupled and global genomic repair of DNA lesions in
Escherichia coli
(adapted from Ref.
1
). (A) These steps are specific to transcription-coupled repair. (B) These steps
are common to transcription-coupled repair and global genomic repair. Although the figure depicts
the dissociation of RNA polymerase after the UvrAB* complex has been recruited, the sequence of
these events is not known. The relative sizes of the nucleic acids and proteins depicted may not
reflect their actual sizes and conformations.
